The sympathomedullary pathway (SAM)

Acute (short-term) stress is handled by the sympathomedullary pathway:

• A stressor is perceived, and the hypothalamus activates the sympathetic branch of the autonomic nervous system.
• The sympathetic branch stimulates the adrenal medulla (the inner part of the adrenal gland), which releases adrenaline and noradrenaline into the bloodstream.
• The result is the fight or flight response: increased heart rate and blood pressure, more blood to the muscles, faster breathing, dilated pupils, sweating, suppressed digestion.
• When the threat passes, the parasympathetic branch restores the body to its resting state ('rest and digest').

Selye's General Adaptation Syndrome (GAS, 1936). Selye exposed rats to a wide range of different stressors (cold, injury, toxic injections) and observed the same physiological response every time — which led him to argue the stress response is non-specific: the body responds in the same way whatever the stressor. GAS has three stages:

• 1. Alarm — the threat is perceived; adrenaline is released; fight or flight is triggered.
• 2. Resistance — the body adapts to the continuing stressor and appears to be coping. Cortisol is released and the body's resources are steadily depleted, but outwardly the person seems normal.
• 3. Exhaustion — the body's resources are used up. The physiological systems can no longer function normally, and stress-related illnesses appear: high blood pressure, ulcers, immune suppression, depression.

Evaluation: Selye's model was hugely influential, but the claim that the response is non-specific is disputed: Mason (1971) measured stress hormones in monkeys and found different levels of adrenaline and noradrenaline depending on the type of stressor, and that stressors producing fear, anger or uncertainty gave different hormonal profiles. GAS also generalises from rats to humans and ignores the cognitive element — as Lazarus argued, whether an event is a stressor depends on how the person appraises it, and the same event stresses one person and not another.

The HPA system and cortisol

Chronic (long-term) stress is handled by the hypothalamic-pituitary-adrenal (HPA) system, which is slower and hormone-driven:

• The hypothalamus releases corticotrophin-releasing hormone (CRH) into the bloodstream.
• CRH causes the pituitary gland to release adrenocorticotrophic hormone (ACTH).
• ACTH travels to the adrenal cortex (the outer part of the adrenal gland), which releases cortisol.

Cortisol has useful short-term effects — it makes stored glucose available for energy and reduces inflammation and pain sensitivity. But chronically raised cortisol suppresses the immune system and impairs cognitive performance, which is why long-term stress is so damaging to health.

Note for the exam: get the two pathways the right way round. SAM = fast, nervous, adrenaline, adrenal medulla, acute. HPA = slow, hormonal, cortisol, adrenal cortex, chronic. The negative feedback loop that normally shuts the HPA system down is thought to become dysregulated in chronic stress and in depression.

Which pathway?

Immunosuppression and cardiovascular disorders

Immunosuppression. Chronically elevated cortisol suppresses the activity of the immune system, particularly the lymphocytes (T-cells, B-cells and natural killer cells) that fight infection.

• Kiecolt-Glaser et al. (1984) took blood samples from 75 first-year medical students one month before their final exams (low stress) and during the exam period (high stress). Natural killer cell activity was significantly reduced in the second sample — direct evidence that a real-life stressor suppresses immune function. The reduction was greatest in students who also reported loneliness and other life events.
• Kiecolt-Glaser et al. (1995) — wound healing. A small punch biopsy wound was made in 13 women caring for a relative with dementia (chronic stress) and in a matched control group. The carers' wounds took significantly longer to heal — on average about 24% longer — providing evidence that chronic stress impairs a real, measurable physiological process.

Cardiovascular disorders. Repeated activation of the stress response raises heart rate and blood pressure, causing wear on the blood vessels; cortisol also raises blood glucose and cholesterol. This contributes to hypertension, atherosclerosis and coronary heart disease (CHD). Stress also causes indirect harm by promoting smoking, drinking and poor diet — behaviours that are themselves risk factors.

Evaluation: stress-illness research is inevitably correlational, so we cannot be certain stress causes the illness — the immunosuppression may be caused by the poor sleep, poor diet and lack of exercise that accompany stressful periods, which are confounding variables. The relationship is also not simple: acute, short-term stress can actually enhance immune function (an adaptive response preparing the body for wounding), and it is chronic stress that suppresses it. Individual differences matter greatly, which is why we turn to personality and hardiness.

Life changes, daily hassles and workplace stress

• Life changes. Holmes and Rahe (1967) developed the Social Readjustment Rating Scale (SRRS) from the medical records of 5,000 patients. Any change — good or bad — requires psychological readjustment and is therefore a stressor. Each of the 43 life events was given a value in life change units (LCUs), with death of a spouse the highest at 100 and divorce at 73. A participant's LCU total over the previous year predicts illness. Rahe et al. (1970) gave the SRRS to 2,664 US Navy personnel before a tour of duty and found a positive correlation of about +0.118 between LCU score and subsequent illness — statistically significant, but a weak relationship.
• Daily hassles. Kanner et al. (1981) devised the Hassles and Uplifts Scale and found that the frequency and intensity of everyday hassles (losing your keys, traffic, arguments) were a better predictor of psychological symptoms than the major life events on the SRRS. Two explanations: the accumulation effect (small stressors add up) and the amplification effect (a person already drained by a major life change is far more vulnerable to daily hassles).
• Workplace stress. Marmot et al. (1997) — the Whitehall II study. Over 7,000 British civil servants were followed. The key finding was that those in the lowest employment grades — with the least job control — had a significantly higher risk of developing cardiovascular disorder than those in the highest grades, even after controlling for other risk factors. Job control, not workload, was the crucial variable. The job strain model holds that stress is highest when demands are high and control is low.

Evaluation: the SRRS treats all change as stressful and does not distinguish desirable from undesirable events, or take account of how individuals appraise them — marriage is scored the same for everyone. It is also retrospective, relying on people to remember accurately what happened over a year. Whitehall II has real practical value — it has driven workplace policy on autonomy and job design — but it is a correlational study of a very specific population (British civil servants), so we should be cautious about generalising to other kinds of work.

Read Whitehall II

Personality type and hardiness

• Type A personality (Friedman and Rosenman, 1974) — time urgency (impatience, working against the clock), competitiveness and achievement-striving, and hostility (easily angered, aggressive). In a longitudinal study, 3,154 American men aged 39–59 were assessed for personality type and followed for 8½ years. Of the 257 men who developed coronary heart disease during the study, about 70% were Type A — roughly twice the rate of Type B men, even after controlling for lifestyle factors.
• Type B — relaxed, patient, non-competitive: lower risk. Type C (Temoshok) — suppresses emotion, is passive and conflict-avoidant, and has been linked to cancer, though the evidence is much weaker.
• Hardiness (Kobasa, 1979) — a protective personality factor. The three Cs:
  • Control — a belief that one can influence events (a strong internal locus of control).
  • Commitment — a sense of involvement and purpose in what one does, rather than alienation.
  • Challenge — seeing change as an opportunity to develop rather than as a threat.
  Kobasa studied 800 American business executives using the SRRS and found that many with high stress scores did not become ill. Those who stayed healthy scored highly on all three Cs.

Evaluation: later research has narrowed the Type A finding considerably: it is now widely accepted that hostility is the toxic component, and that time-urgency and competitiveness on their own are much less predictive — so the original Type A construct is too broad. There is also a question of direction: hardiness may simply be another way of describing an internal locus of control (a criticism made of Kobasa's measure), and the hardiness questionnaire measures its absence (alienation, powerlessness) rather than its presence. Personality research is also correlational, and a third variable — genetics, for example — could produce both a Type A personality and a vulnerable cardiovascular system.

Drugs, SIT, biofeedback, social support and gender

• Drug therapy. Benzodiazepines (BZs) — e.g. Librium, Valium. They enhance the action of GABA, the body's natural anxiety-reducing neurotransmitter, which makes neurons less likely to fire, producing a general calming effect. Beta blockers (BBs) — act on the heart and the cardiovascular system rather than the brain, blocking the action of adrenaline and noradrenaline on beta-adrenergic receptors, so heart rate and blood pressure fall. Musicians and snooker players have used them to steady their hands. Strengths: fast, effective and easy. Weaknesses: BZs cause dependence, withdrawal and tolerance, and they treat only the symptoms, never the source of the stress.
• Stress inoculation training (Meichenbaum, 1985) — a cognitive-behavioural approach in three phases. 1. Conceptualisation — the therapist and client discuss the stressors and re-frame them in a more manageable way. 2. Skills acquisition and rehearsal — the client learns and practises coping skills: relaxation, positive self-talk ('I can handle this'), social skills. 3. Application and follow-through — the skills are practised in progressively more demanding real-life situations, with role-play, and then applied. Strength: it treats the cause as well as the symptom, and gives lasting protection. Weakness: it is time-consuming, expensive and demands a high level of commitment.
• Biofeedback — the client is connected to a machine that provides real-time feedback about an involuntary physiological function (heart rate, muscle tension), learns relaxation techniques, and is reinforced (by the visible fall in the reading) when they succeed. It is essentially operant conditioning applied to the ANS, and the skill can eventually be transferred to real life without the machine.
• Social support — instrumental (practical help), emotional (comfort and reassurance) and esteem support (encouraging self-belief). It acts as a buffer against the health effects of stress.
• Gender differences in coping. Taylor et al. (2000) argued the fight-or-flight account is androcentric, and proposed that women are more likely to respond with 'tend and befriend': protecting offspring (tending) and forming alliances with other women (befriending). This is thought to be mediated by oxytocin, whose effects are enhanced by oestrogen and reduced by testosterone. Women are also more likely to use emotion-focused coping and to seek social support; men are more likely to use problem-focused coping — though the difference is one of degree, not kind.

Which management technique?

Measuring stress: self-report and physiological measures

Self-report scales

• The Social Readjustment Rating Scale (SRRS) — Holmes and Rahe's 43 life events, each weighted in life change units (death of a spouse = 100, divorce = 73). The respondent ticks the events experienced in the past year and the LCUs are totalled. Strength: quick, standardised and easy to compare between people. Weaknesses: it is retrospective (recall over a year is unreliable), it treats every event as equally stressful for everyone, and it does not distinguish desirable from undesirable change.
• The Hassles and Uplifts Scale (Kanner et al.) — measures the frequency and intensity of everyday irritations and everyday pleasures. It predicts psychological symptoms better than the SRRS, and it captures the small, chronic stressors that dominate most people's lives. But it is still self-report, and therefore vulnerable to social desirability bias and to the respondent's current mood: a person who is already depressed will rate ordinary events as more hassling.

Physiological measures

• Skin conductance response (SCR) — also called galvanic skin response. Under sympathetic arousal the sweat glands become more active, and because sweat conducts electricity, the electrical conductance of the skin rises. Electrodes on the fingers measure this directly, giving an objective, moment-by-moment index of arousal that the participant cannot fake.
• Other physiological measures include heart rate, blood pressure and assays of cortisol in blood or saliva.

Evaluation: physiological measures are objective and free from social desirability bias — a decisive advantage over self-report. But they are indirect: skin conductance rises with any sympathetic arousal, including excitement, exercise or even a warm room, so a high reading does not necessarily mean stress. They also say nothing about the cognitive appraisal that makes an event stressful in the first place. The best research therefore triangulates, combining self-report with physiological measurement.

Selye's stages

Criticising Selye

Which type of support?

Beta blockers

Hardiness

The Type A refinement

SAM, HPA or coping?

Tap a card, then where it belongs. Getting the two stress pathways straight is worth easy marks.

Study and finding

Tap an item on the left, then its partner on the right.

The big ideas to know

You have covered the whole of AQA 4.3.7 Stress. Press Finish to see your score.